CN106443880B

CN106443880B - Demultiplexer with blazed waveguide side wall grating and sub-wavelength grating structures

Info

Publication number: CN106443880B
Application number: CN201610970200.9A
Authority: CN
Inventors: 韩佳晖; 张艳; 梁家理
Original assignee: China Jiliang University
Current assignee: China Jiliang University
Priority date: 2016-11-02
Filing date: 2016-11-02
Publication date: 2023-03-10
Anticipated expiration: 2036-11-02
Also published as: CN106443880A

Abstract

A demultiplexer with blazed waveguide side-wall grating and sub-wavelength grating structure comprises a receiver waveguide array, a sub-wavelength grating, a blazed side-wall grating, a Roland circle and SiO ₂ A layer and a Si layer. The receiver waveguide array is arranged on a Rowland circle and tangent to the waveguide direction in the input blazed side wall grating, and the refractive index AR boundary of the sub-wavelength grating is parallel to the blazed side wall grating and is positioned in SiO ₂ On the layer, two sets of SiO ₂ The layer and the Si layer are alternately covered, the Si layer is arranged at the lowest part, and SiO is arranged ₂ The layer is the uppermost layer. The invention can realize that the diffracted light with different wavelengths is intercepted by corresponding receivers, is particularly promising for the application in optical interconnection and coarse wavelength division multiplexing, and has the advantages of compact size, broadband operation and customized passband.

Description

Demultiplexer with blazed waveguide side wall grating and sub-wavelength grating structure

Technical Field

The present invention relates to a demultiplexer with a grating structure, and more particularly, to a demultiplexer with blazed waveguide side-wall gratings and sub-wavelength grating structures.

Background

In the field of spectroscopy and sensing, arrayed waveguide grating and echelle grating based wavelength demultiplexers have been used in wavelength division multiplexed communication networks, and the high refractive index contrast of silicon-on-insulator (SOI) platforms allows sub-micron sized waveguides and waveguide bend radii as small as a few microns, thereby significantly reducing the size of the device. Until now, several very compact arrayed waveguide gratings using SOI waveguides have been reported, however, also very compact arrayed waveguide grating demultiplexers have scattering loss and phase error due to waveguide sidewall roughness, both of which limit crosstalk performance since phase delay occurs in slab waveguides but not in waveguide arrays, i.e. a demultiplexer based on planar waveguide intermediate gratings can avoid some problems.

Diffraction gratings, an important light splitting device, are increasingly used in emerging fields such as imaging, information processing, metering, integrated optics, and optical communications, and when the gratings are scribed into zigzag line groove cross sections, the light energy of the gratings is concentrated in a predetermined direction, i.e., on a certain level of spectrum of the blazed gratings. When the direction is detected, the intensity of the spectrum is maximum, and the diffraction efficiency of the grating is greatly improved.

Several demultiplexer devices based on waveguide echelle gratings have also been recently manufactured in silicon and silica layers and SOI waveguides, and the main challenges in manufacturing echelle grating demultiplexers are to make smooth vertical grating faces, control polarization dependent wavelength drift, and reduce polarization dependent losses, which have been successfully overcome in glass waveguide based echelle grating devices, but not fully solved in silicon-on-insulator based devices.

SOI-based optical waveguide devices have been rapidly developed because of the extremely low transmission loss of SOI. For a common optical waveguide, light travels along the core layer where the refractive index is high. However, as the size of the waveguide becomes smaller and smaller with the application of the optical waveguide in an integrated module, the roughness caused by etching greatly increases the loss of the waveguide during the manufacturing process of the waveguide. The presence of the sub-wavelength grating waveguide reduces the effect of etch roughness on waveguide loss, while also providing a waveguide structure that can tailor the refractive index of the material.

Disclosure of Invention

To address the deficiencies of the prior art, the present invention provides a demultiplexer with blazed waveguide sidewall grating and sub-wavelength grating structures that enables interception of different wavelengths, is particularly promising for applications in optical interconnects and coarse wavelength division multiplexing, and has the advantages of compact size, broadband operation, and customized passband.

The technical scheme adopted by the invention for solving the technical problem is as follows:

a demultiplexer with blazed waveguide side wall grating and sub-wavelength grating structures comprises a receiver waveguide array (1), a sub-wavelength grating (7), a blazed side wall grating (3), a Rowland circle (4), and SiO ₂ A layer (5) and a Si layer (6), wherein the receiver waveguide array (1) is on a Rowland circle (4) with radius R and tangent to the waveguide direction in the input blazed sidewall grating (3), the sub-wavelength grating refractive index AR boundary (2) is parallel to the blazed sidewall grating (3), two sets of SiO are parallel ₂ The layer (5) and the Si layer (6) are alternately covered, the Si layer (6) is arranged at the lowest part, and SiO is arranged ₂ The layer (5) is arranged at the top, and the blazed side wall grating (3) and the sub-wavelength grating (7) are arranged at the top.

The blazed side wall grating (3) is formed by a curved silicon waveguide to provide focusing, and is in an arc shape with the central wavelength focus of the demultiplexer as the center and the radius of 2R.

The occupied area of the demultiplexer device is 90 micrometers multiplied by 140 micrometers, the wavelength interval of the demultiplexer device is 25nm, 15 channels are formed, and the demultiplexer device has a 375nm working broadband.

The sub-wavelength grating (7) adopts a refractive index AR boundary (2) of a triangular tooth sub-wavelength grating.

The invention has the beneficial effects that: the Fresnel reflectivity of the boundary (2) of the refractive index AR of the triangular tooth-shaped sub-wavelength grating used and arranged at the boundary between the groove and the plate-shaped area of the section of the silicon waveguide is reduced, and the sub-wavelength property of the grating is suppressed. The sub-wavelength grating refractive index AR boundary (2) is easier to produce and also provides a larger spectral bandwidth than a single layer AR coating. Furthermore, the designed multiplexer can be extended to applications in the field of dense optical wave multiplexing by increasing the radius of the rowland circle (4), thereby creating a larger channel spacing in the focal plane, and unlike echelle gratings, the present device allows modification of the spacing and apodization of the grating to change the phase and intensity of the derivative field, and furthermore, another advantage of the design is that no waveguide phased array is required, which means a distinct advantage of smaller device size compared to AWGs, since the light propagates in a single waveguide, thus reducing the total loss due to waveguide defects and the effect of phase error accumulation.

Drawings

The invention is further described with reference to the accompanying drawings and the detailed description.

Fig. 1 is a schematic structural diagram of a blazed grating waveguide side wall and a sub-wavelength grating structure demultiplexer according to the present invention.

Fig. 2 is a schematic diagram of a blazed grating waveguide sidewall and a sub-wavelength grating structure demultiplexer grating sidewall and a sub-wavelength grating according to the present invention.

In the figure, 1 is a receiver array waveguide; 2 is a boundary of a sub-wavelength grating refractive index AR; 3 is a blazed grating side wall; 4 is a Rowland circle; 5 is SiO ₂ A layer; 6 is a Si layer; and 7 is a sub-wavelength grating.

Detailed Description

In FIG. 1, a blazeThe demultiplexer of the waveguide side wall grating and sub-wavelength grating structure comprises a receiver waveguide array 1, a sub-wavelength grating refractive index AR boundary 2, a blazed side wall grating 3, a Rowland circle 4 and SiO ₂ Layer 5, si layer 6 and sub-wavelength grating 7. The receiver waveguide array 1 is arranged on a Rowland circle 4 and is tangent to the waveguide direction in the input blazed side wall grating 3, the boundary 2 of the refractive index AR of the sub-wavelength grating is approximately parallel to the blazed side wall grating 3, the blazed side wall grating 3 is formed by a curved silicon waveguide to provide focusing, and the blazed side wall grating is an arc with the central wavelength focus of the demultiplexer as the center and the radius of 2R.

In FIG. 2, the three-dimensional cross section of the sub-wavelength grating 7 and the blazed side-wall grating 3 in the demultiplexer with the structure of the blazed waveguide side-wall grating and the sub-wavelength grating of the invention, wherein the refractive index AR boundary 2 of the sub-wavelength grating is parallel to the blazed side-wall grating 3, and two groups of SiO are parallel ₂ Layer 5 and Si layer 6 are alternately overlaid, with Si layer 6 being positioned lowermost, siO ₂ The layer 5 is placed on top with the blazed sidewall grating 3 and the sub-wavelength grating 7 uppermost.

Claims

1. A demultiplexer with blazed waveguide side-wall grating and sub-wavelength grating structure comprises a receiver waveguide array, a sub-wavelength grating, a blazed side-wall grating, a Rowland circle, and SiO ₂ A layer and a Si layer, wherein the receiver waveguide array is on a Rowland circle with radius R and tangent to the waveguide direction in the input blazed sidewall grating, the sub-wavelength grating refractive index AR boundary is parallel to the blazed sidewall grating, and two sets of SiO are parallel ₂ The layers are alternately covered with a Si layer, the Si layer is arranged at the lowest part, and SiO is arranged ₂ The layer is on the superiors, and blazed lateral wall grating and sub-wavelength grating are in the top, its characterized in that: the blazed side wall grating is an arc with the radius of 2R and the center wavelength focus of the demultiplexer is used as the center, the sub-wavelength grating adopts triangular teeth, and the demultiplexer can change the phase and the strength of a derivative field through modification of the distance and apodization of the grating.

2. A demultiplexer having a blazed waveguide side-wall grating and a sub-wavelength grating structure as claimed in claim 1, wherein: the radius of the Rowland circle can be expanded.

3. A demultiplexer having a blazed waveguide sidewall grating and a sub-wavelength grating structure as defined in claim 1, wherein: the occupied area of the demultiplexer device is 90 Mum multiplied by 140 Mum, the wavelength interval of the device is 25nm, 15 channels are formed, and a 375nm working broadband is formed.